Typically, a column is industrially used as an apparatus for distillation, absorption, or cooling in petroleum, oil refinery, chemistry, and fine chemistry industries or for removal of toxic gases or organic substances. The column separates, absorbs, or condenses separable components through gas-liquid contact.
Recently, as a system for fractionating two or more components from each other, a dividing wall column (also called divided wall column or partitioned distillation column) is used to save energy and capital cost. A dividing wall column has a structure combining functions of two or more different columns. The side as well as the top and bottom of the diving wall column are provided with one or more discharge holes. The dividing wall column is characterized to be equipped with one or more internal vertical walls which divide the internal space into two or more sections. In the dividing wall column, liquid flowing down from above the dividing walls needs to be split as desired into different sections divided by the walls. When the liquid is split, a liquid splitter is used to adjust a liquid split ratio.
However, the conventional dividing wall column for distillation, absorption, or cooling has a problem that it can control only a liquid split ratio but cannot control a vapor split ratio.
To address this problem, according to a conventional method of determining a vapor split ratio, the vapor split ratio is fixed at the designing stage according to the size of a chimney on a chimney tray through which vapor or gas can pass. The vapor split ratio determined according to the size of the chimney is unchangeable with operation conditions. Therefore, it was difficult to satisfactorily accomplish the energy saving effect that is the advantage of the dividing wall column.
According to another conventional method of adjusting a vapor split ratio, gas in a lower space of a column is prevented from rising to an upper space through the column, but the gas is indirectly guided to the upper space via a pipeline disposed outside the column and connected to the upper space of the column. In this case, the flow of the gas is controlled by a valve installed on the pipeline disposed outside the column. This method is problematic in that it requires a large installation space and suffers high pressure loss attributable to the valve.
According to a further conventional method of adjusting a vapor split ratio, a perforated plate is installed on a gas flow path, and a liquid layer is provided on the perforated plate to cause the gas to pass through the liquid layer. In this case, the height of the liquid surface is changed to control the flow resistance by which the vapor split ratio can be adjusted. However, this method is disadvantageous in terms of entrainment that occurs when the gas passes through the liquid layer. The entrainment negatively affects operation performance of a distillation column.
There are conventional arts related to the present invention: Korean Patent Application Publication No. 2010-0092349 (titled “Division Wall Column Characterized By That Pressure In Dichotomous Spaces Is Substantially Equivalent”); and U.S. Pat. No. 8,562,792 B2 (titled “Vapor And Liquid Flow Control In A Dividing Wall Fractional Distillation Column).